The present invention relates to stacking apparatus and more particularly to apparatus for stacking layers or tiers of articles by introducing each successive layer from the bottom of the tiered layers.
In the transport or storage of generally rectangular articles such as cartons, paper bales and the like, it is highly desirable to stack the articles in successive or tiered layers. The tiered articles are easily handled on a pallet by conventional forklift trucks. Various types of apparatus have been proposed for palletizing or cubing such articles for transport and/or storage. The presently available apparatus employs one of several different approaches or methods to palletize. Some of these apparatus successively lower a support member and introduce successive layers on top of the stacked tiers. An example of an apparatus operating in accordance with this method may be found in U.S. Pat. No. 3,986,621, entitled Flap Sensor and Hoist Position Control for Palletizer and issued in the name of Robert E. Bowser on Oct. 19, 1976. The apparatus disclosed in this patent includes a hoist supporting a pallet. The hoist is lowered in incremental stages as each successive layer of articles is stacked thereon at approximately the same horizontal level.
Another method employed by presently available stacking apparatus involves raising each successive layer of articles and placing the layer on top of the previously stacked layers of articles. A still further method involves stacking by introducing successive layers from the bottom of the previously stacked layers of articles. The first layer of articles is raised vertically, a successive layer of articles is introduced underneath the raised layer and the raised layer is lowered onto the successive layer. This cycle is repeated until the desired number of tiers or layers of articles is obtained. An example of this type of apparatus may be found in U.S. Pat. No. 3,904,045 entitled Machine for Loading Packages on a Pallet and issued in the name of Thibault on Sept. 9, 1975. The apparatus disclosed in this patent includes a pair of successively and sequentially operated fork members one on each side of a roller conveyor. The fork members are operated independently for successively lifting the layers of packages so as to permit another layer of packages to be introduced underneath those supported by the forks.
This later method of stacking may also be employed to stack individual cartons. For example, as shown in U.S. Pat. No. 3,866,763 entitled Automatic Case Stacker and issued in the name of Alduk on Feb. 18, 1975, individual cartons are raised by a powered ram. The carton is then clamped in the raised position. The ram is lowered and a successive carton is introduced underneath the raised carton. The raised carton is then unclamped and it is lowered onto the successively introduced carton.